Incorporeal or uncarnate means without a physical body, presence or form. It is often used in reference to souls, spirits, and God in many religions including Judaism, Christianity, and Islam. In ancient philosophy, any attenuated "thin" matter such as air, ether, fire or light was considered incorporeal. The ancient Greeks believed air, as opposed to solid earth, to be incorporeal, in so far as it is less resistant to movement; and the ancient Persians believed fire to be incorporeal in that every soul was said to be produced from it. In modern philosophy, a distinction between the incorporeal and immaterial is not necessarily maintained: a body is described as incorporeal if it is not made out of matter.